Ceramic matrix composite-based seal

ABSTRACT

A seal includes a ceramic matrix composite ply having woven ceramic-based fibers in a ceramic-based matrix. The ceramic matrix composite ply has at least one bend formed about a bend axis and defines at least one rounded portion. A sealed assembly and a method of making a seal are also disclosed.

BACKGROUND

A gas turbine engine typically includes a fan section, a compressorsection, a combustor section and a turbine section. Air entering thecompressor section is compressed and delivered into the combustionsection where it is mixed with fuel and ignited to generate ahigh-energy exhaust gas flow. The high-energy exhaust gas flow expandsthrough the turbine section to drive the compressor and the fan section.The compressor section typically includes low and high pressurecompressors, and the turbine section includes low and high pressureturbines.

Various components in the gas turbine engine include seals to controlairflow, such as cooling airflow, within the engine. Some of the gasturbine engine operate at very high temperatures and/or pressures. Theseals must withstand the operating conditions of the section of the gasturbine engine in which they are situated.

SUMMARY

A seal, according to an example of this disclosure includes a ceramicmatrix composite ply having woven ceramic-based fibers in aceramic-based matrix. The ceramic matrix composite ply has at least onebend formed about a bend axis and defines at least one rounded portion.

In a further example of the foregoing, at least one bend includes afirst bend and a second bend.

In a further example of any of the foregoing, the first bend is formedabout a first bend axis and the second bend is formed about a secondbend axis. The first bend axis and second bend axis are parallel to oneanother.

In a further example of any of the foregoing, at least one bend definesa tube shape.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers. The first set of fibers are angled with respect tothe bend axis at an angle between about 0 and 60 degrees.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers. The relative volume fractions of the first set offibers and the second set of fibers is between about 5% and 60%.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers. The relative volume fractions of the first set offibers and the second set of fibers are between about 5% and 60%. Thefirst set of fibers are angled with respect to the bend axis at an anglebetween about 0 and 60 degrees.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction. Asecond set of fibers are oriented in a second direction and woven withthe first set of fibers. A third set of fibers are oriented in a thirddirection and woven with the first and second sets of fibers.

A sealed assembly according to an example of this disclosure includes afirst component, a second component, and a seal sealing the firstcomponent with respect to the second component. The seal includes aceramic matrix composite ply which has woven ceramic-based fibers in aceramic-based matrix. The ceramic matrix composite ply has at least onebend formed about a bend axis and defines at least one rounded portion.

In a further example of the foregoing, at least one bend includes afirst bend and a second bend.

In a further example of any of the foregoing, the first bend is formedabout a first bend axis and the second bend is formed about a secondbend axis. The first bend axis and second bend axis are parallel to oneanother.

In a further example of any of the foregoing, at least one bend definesa tube shape.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers. The first set of fibers are angled with respect tothe bend axis at an angle between about 0 and 60 degrees.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers. The relative volume fractions of the first set offibers and the second set of fibers is between about 5% and 60%.

In a further example of any of the foregoing, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers. The volume fractions of the first set of fibers andthe second set of fibers are between about 5% and 60%. The first set offibers are angled with respect to the bend axis at an angle betweenabout 0 and 60 degrees.

In a further example of any of the foregoing, each the first and secondcomponents have at least one mating face mating with the seal. At leastone mating face is non-abrasive with respect to the seal.

In a further example of any of the foregoing, the sealed component is ina gas turbine engine.

A method of making a seal according to an example of this disclosureincludes forming a single ply comprising woven ceramic-based fibers in aceramic-based matrix to include at least one bend about a bend axis. Thewoven ceramic-based fibers define a weave direction, the woven ceramicbased fibers include a first set of fibers oriented in a first directionand a second set of fibers oriented in a second direction and woven withthe first set of fibers. The first set of fibers are angled with respectto the bend axis at an angle between about 30 and 60 degrees.

In a further example of the foregoing, the forming includes forming afirst bend, and forming a second bend after forming the first bend.

In a further example of any of the foregoing, the forming includesintroducing the at least one bend, and rigidizing the ply afterintroducing the bend.

Although the different examples have the specific components shown inthe illustrations, embodiments of this invention are not limited tothose particular combinations. It is possible to use some of thecomponents or features from one of the examples in combination withfeatures or components from another one of the examples.

These and other features disclosed herein can be best understood fromthe following specification and drawings, the following of which is abrief description.

Although the different examples have the specific components shown inthe illustrations, embodiments of this invention are not limited tothose particular combinations. It is possible to use some of thecomponents or features from one of the examples in combination withfeatures or components from another one of the examples.

These and other features disclosed herein can be best understood fromthe following specification and drawings, the following of which is abrief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an example gas turbine engine.

FIGS. 2A-C schematically show example seals for the gas turbine engineof FIG. 1.

FIGS. 3A-C shows a detail view of the seal of FIG. 2A.

FIGS. 4A-B show a detail view of another example seal of FIG. 2A.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. The fan section 22 drivesair along a bypass flow path B in a bypass duct defined within a nacelle15, and also drives air along a core flow path C for compression andcommunication into the combustor section 26 then expansion through theturbine section 28. Although depicted as a two-spool turbofan gasturbine engine in the disclosed non-limiting embodiment, it should beunderstood that the concepts described herein are not limited to usewith two-spool turbofans as the teachings may be applied to other typesof turbine engines including three-spool architectures.

The exemplary engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. Terms such as “axial,” “radial,”“circumferential,” and variations of these terms are made with referenceto the engine central axis A. It should be understood that variousbearing systems 38 at various locations may alternatively oradditionally be provided, and the location of bearing systems 38 may bevaried as appropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects, a first (or low) pressure compressor 44 and a first (orlow) pressure turbine 46. The inner shaft 40 is connected to the fan 42through a speed change mechanism, which in exemplary gas turbine engine20 is illustrated as a geared architecture 48 to drive a fan 42 at alower speed than the low speed spool 30. The high speed spool 32includes an outer shaft 50 that interconnects a second (or high)pressure compressor 52 and a second (or high) pressure turbine 54. Acombustor 56 is arranged in exemplary gas turbine 20 between the highpressure compressor 52 and the high pressure turbine 54. A mid-turbineframe 57 of the engine static structure 36 may be arranged generallybetween the high pressure turbine 54 and the low pressure turbine 46.The mid-turbine frame 57 further supports bearing systems 38 in theturbine section 28. The inner shaft 40 and the outer shaft 50 areconcentric and rotate via bearing systems 38 about the engine centrallongitudinal axis A which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 whichare in the core airflow path C. The turbines 46, 54 rotationally drivethe respective low speed spool 30 and high speed spool 32 in response tothe expansion. It will be appreciated that each of the positions of thefan section 22, compressor section 24, combustor section 26, turbinesection 28, and fan drive gear system 48 may be varied. For example,gear system 48 may be located aft of the low pressure compressor, or aftof the combustor section 26 or even aft of turbine section 28, and fan42 may be positioned forward or aft of the location of gear system 48.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than about ten (10), thegeared architecture 48 is an epicyclic gear train, such as a planetarygear system or other gear system, with a gear reduction ratio of greaterthan about 2.3 and the low pressure turbine 46 has a pressure ratio thatis greater than about five. In one disclosed embodiment, the engine 20bypass ratio is greater than about ten (10:1), the fan diameter issignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 has a pressure ratio that is greater thanabout five 5:1. Low pressure turbine 46 pressure ratio is pressuremeasured prior to inlet of low pressure turbine 46 as related to thepressure at the outlet of the low pressure turbine 46 prior to anexhaust nozzle. The geared architecture 48 may be an epicycle geartrain, such as a planetary gear system or other gear system, with a gearreduction ratio of greater than about 2.3:1 and less than about 5:1. Itshould be understood, however, that the above parameters are onlyexemplary of one embodiment of a geared architecture engine and that thepresent invention is applicable to other gas turbine engines includingdirect drive turbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8 Mach andabout 35,000 feet (10,668 meters). The flight condition of 0.8 Mach and35,000 ft (10,668 meters), with the engine at its best fuelconsumption—also known as “bucket cruise Thrust Specific FuelConsumption (‘TSFC’)”—is the industry standard parameter of lbm of fuelbeing burned divided by lbf of thrust the engine produces at thatminimum point. “Low fan pressure ratio” is the pressure ratio across thefan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The lowfan pressure ratio as disclosed herein according to one non-limitingembodiment is less than about 1.45. “Low corrected fan tip speed” is theactual fan tip speed in ft/sec divided by an industry standardtemperature correction of [(Tram ° R)/(518.7° R)]{circumflex over( )}0.5. The “Low corrected fan tip speed” as disclosed herein accordingto one non-limiting embodiment is less than about 1150 ft/second (350.5meters/second).

The present application discloses an elastic or elastic/partiallyinelastic seal made of a single layer of ceramic matrix composite (CMC)that can be shaped into traditional elastic metallic seal shapes but hasmuch greater temperature capability. Inelastic refers in the presentcontext to the ability of the CMC material to deform beyond its elasticlimit with some loss of properties but still providing some sealingcapability.

FIGS. 2A-C schematically show example seals 100/200/300, respectively.The seals 100/200/300 seal a flow area 102 between respective components104/106, for example, in order to control and retain air in a flow area102. For instance, the airflow can be cooling airflow. Maintainingcooling airflow in the flow area 102 can improve cooling efficiency forthe components 104/106.

In one example, the components 104/106 are in e.g., the compressorsection 24, combustor section 26 or turbine section 28 of the engine 20.As an example, the components 104/106 are components of an airfoilassembly, such as in the compressor section 24 or turbine section 28. Ina more particular example, the airfoil assembly includes a ceramic-basedairfoil, such as a ceramic matrix composite (CMC) or a monolithicceramic material, such as a silicon-containing ceramic. Other examplecomponents 104/106 are components of a valve or engine 20 casingstructures.

The seal 100/200/300 is a CMC seal. In general, a CMC includesceramic-based fibers in a ceramic-based matrix. The fibers can becarbide, oxide, or carbon fibers, or a combination thereof, in someexamples. The matrix can be a glass, cermet, or other ceramic-basedmaterial, or combinations thereof. In some examples, the fibers arecoated with an interface coating.

The CMC seal has a matrix density of above about 85%, preferably with noopen porosity and in a particular example above 95% or greater. “Matrixdensity” refers to the density of material around the fiber and in somecases its interphases as measured by traditional techniques known topractitioners in the art.

The CMC seal 100/200/300 withstands high temperatures during operationof the engine 20. Other seals, such as metallic seals, may experiencecreep when exposed to high temperatures, which can reduce their sealingefficiency. Some seals are made from metallic materials with improvedcreep resistance, such as single crystal metallic alloys, however, thosematerials can have high cost and can be difficult to manufacture.Alternatively/additionally, metallic seals will require cooling that mayimpart complexity to the design. The CMC seal 100/200/300 is formed of asingle thin ply, which allows the seal 100/200/300 to have somecompliance, e.g., elastic properties that allow the CMC seal 100/200/300to form/maintain a sealing relationship under compressive loads betweencomponents 104/106. A single ply means that the material is made into asingle layer of woven material without any lamination step.

In one example, the modulus of elasticity of the CMC seal 100/200/300 issimilar to the modulus of elasticity of metallic seals. In a particularexample, the seal 100/200/300 has a modulus of elasticity of about 200GPa. The CMC seal 100/200/300 has high temperature resistance, includingimproved creep resistance as compared to metallic seals. Furthermore,the CMC seal 100/200/300 has a relatively constant modulus of elasticityacross wide temperature ranges, including the high operatingtemperatures of the engine 20.

The example seals 100/200/300 are face seals, e.g. have at least onebend that defines at least one rounded portion about an axis (discussedin detail below), and the sealing surfaces are normal to the axis. Theseal 100/200/300 comprises at least one bend/at least one roundedportion and can in one example include a full circle, e.g., a tubeshape. The example seals 100/200/300 can be axial seals (e.g., subjectto compressive loads in two directions that are normal to one another)or radial seals (e.g., subject to compressive loads in one direction).

The example seal 100 of FIG. 2A is shown in detail in FIGS. 3A-C. Theexample seal 100 has a bend 108 that defines a C-shape or a U-shapeabout an axis B. Though the axis B in this example is linear, the B axisof the bend can follow a circular, partially circular or any othercontour geometry. The exterior of the seal 100 provides a sealingsurface 101 (FIG. 3C). The seal 100 comprises a ply 109 which includesceramic fibers 110 disposed in a ceramic matrix 112. In some examples,the individual woven fibers can be bundles of fibers (known as tows) orribbons of fibers. In further examples, the tows/ribbons can be woven,braided or knitted. The tows/ribbons can be processed prior to formingthe ply 109 with various size or Denier. For instance, the processingmay include flattening tows.

As shown, the woven fibers 110 include at least two sets of fibers 110a/110 b that run in first and second directions, respectively, woventogether. In the example of FIGS. 3A-C, there are two sets of fibers 110a/110 b. The fibers 110 b are oriented at an angle Θ with respect to thefibers 110 a. The angle Θ can vary from 0 to 90 degrees. The first setof fibers 110 a has an angle α (FIG. 3B) relative to the bend axis B ofthe seal 100. The angle α can be anywhere from 0 to 90 degrees.

The elasticity of the ply 109 is directional e.g., it varies fromdirection to direction. The elasticity in each direction is related tothe ratio of amount of fibers 110 a to fibers 110 b, the angle Θ, andthe angle α.

In one example, the ratio of amount of fibers 110 a to 110 b isexpressed as a relative volume fraction. In a particular example, therelative volume fraction is between about 5% and 60%.

The fibers 110 a/110 b are oriented such that the weave direction is atan angle with respect to the axis B as discussed above so that the seal100 has a stiffness that is highest in a direction normal to the axis B.Also, the fibers 110 have a minimum bend radius below which the fibers110 can experience breakage. Accordingly, the fibers are oriented toenable the bend 108 to be formed substantially without any fiber 110breakage.

In general, as a approaches 90 degrees, the stiffness and elastic limitof the seal 100 increases. However, when the fibers 110 are angled withrespect to the bend axis B (e.g., when a is less than 90 degrees), thefibers 110 have a generally higher resistance to breakage. Fiber 110 cangenerally withstand bend 108 radii on the millimeter scale or largerdepending on the fiber diameter and composition. For relatively largebend radii for bend 108, e.g., bend radii on the order of millimeters,in one example, a is about 90 degrees plus/minus 10 degrees. Forrelatively smaller bend radii, in one example, a is less than 90degrees.

In general, an angle Θ that approaches 45 degrees results in a morecompliant ply 109 along the bend axis B. In a particular example, theangle Θ is between about 0 and 60 degrees. In a more particular example,the angle Θ is between about 30 and 60 degrees.

In general, the more fibers 110 a, the less compliant (stiffer) the ply109 is with respect to the direction of bending at bend 108. In oneexample, the set of fibers 110 b comprises more fibers than the set offibers 110 a. In other words, the weave has more fibers 110 b running inthe first direction than in the second direction. In a particularexample the volume fractions of fibers 110 a and fibers 110 b in thecomposite are between about 5% and 60%.

FIGS. 4A-B show another example seal 150 like the seal 100. The seal 150is formed from a ply 159, which in example in FIG. 4B includes threesets of fibers (or tows/ribbons) 110 d, 110 e, 110 f woven together intoa triaxial braid. In the particular example of FIG. 4A, the ply 159includes fibers 110 woven in a three-dimensional woven angle interlockarchitecture where fibers 110 d are at an angle α=0 degrees (e.g., arealigned with) with bend axis B and fibers 110 e, 110 f are interlacingthe fiber 110 d.

As shown in the above examples, the seals 100/150 comprise a single ply109/159. The single-ply composition of the seal 100/150 enables bendingabout bend axis B as discussed above because the compliant nature of CMCmaterials varies inversely with the thickness of the ply 109/159. In aparticular example, the thickness of the ply 109/159 is less than about200 microns (0.008 inches).

To make the seal 100/150, the ply 109/159 is made according to any knownmethod. For instance, the fibers 110 are arranged as discussed above andinfiltrated with the matrix material 112. The fibers 110 may also becoated with an interface material or protective coating prior or aftertheir placement into a woven structure and prior to matrix infiltration,as would be known in the art. Other methods of making CMC are known inthe art and can be implemented to make the ply 109/159. In oneimplementation, the fibers 110 can be woven into a ply 109/159 and thenformed to include the bend 108 using tooling, such as on a mandrel tointroduce the bend 108. Once the bend 108 is introduced, the ply 109/159is densified and/or rigidized according to known methods to retain thebend 108. In another example, the seal 100/150 is formed by any knownmolding technique suitable for CMC materials. In another example, theseal 100/150 is formed by making a CMC tube and cutting the tube alongits axis. In any of these examples, mating surfaces can be formed in theseal, depending on geometry of the components 104/106 which are to besealed with the seal 100/150. In some examples, a coating can be appliedto the sealing surface 101 (FIG. 3C) to smooth/protect the surface andimprove the sealing efficiency of the seal 100.

FIG. 2B shows another example seal 200. In this example, the seal 200includes two elements 200 a/200 b. Both elements 200 a/200 b arecomprised of a ply 109 like the ply 109 of seal 100. Element 200 a is aU-shape like seal 100/150. Element 200 b, which is disposed insideelement 200 a, is a tube shape. Both elements 200 a/200 b are bent aboutthe same axis B. The element 200 b provides an added measure ofleak-tightness for the seal 200, for instance, for high-compressive-loadapplications. Alternatively, 200 a can be metallic to improve sealingperformance and 200 b provides support, stiffness and creep resistance.The seal 200 can incorporate any of the features discussed above withrespect to the seals 100/150.

FIG. 2C shows another example seal 300. The seal 300 is comprised of aply 109/159 like the ply 109/159 of seal 100/150. Seal 300 includes twobends 108 about axes B, B′ that define a W-shape. The axes B, B′ areparallel to one another. Accordingly, the weave direction of the ply109/159 is the same with respect to both axes B, B′. Each of the twobends 108 are formed in succession in the ply 109 as discussed above.The seal 300 can incorporate any of the features discussed above withrespect to the seals 100/150.

The components 104/106 have mating faces 114 (FIGS. 2A-C) which engagethe seal 100/200/300. In one example, the mating faces 114 aredeformable with respect to the seal 100/200/300. For example, the matingfaces 114 can include a coating that is plastic with respect to theseal, or can be polished/smooth.

The example seals 100/200/300 have particular geometries, but it shouldbe understood that other geometries or combinations of geometries arecontemplated. For instance, a tube shape like the element is 200 b ofthe seal 200 can be used as a seal on its own. As another example, aseal can have more than two bends to define an undulating shape. To thatend, although the different examples are illustrated as having specificcomponents, the examples of this disclosure are not limited to thoseparticular combinations. It is possible to use some of the components orfeatures from any of the embodiments in combination with features orcomponents from any of the other embodiments.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A seal, comprising: a ceramic matrix compositeply having woven ceramic-based fibers in a ceramic-based matrix, theceramic matrix composite ply having at least one bend formed about abend axis and defining at least one rounded portion.
 2. The seal ofclaim 1, wherein the ceramic matrix composite ply includes a first bendand a second bend.
 3. The seal of claim 2, wherein the first bend isformed about a first bend axis and the second bend is formed about asecond bend axis, wherein the first bend axis and second bend axis areparallel to one another.
 4. The seal of claim 1, wherein the at leastone bend defines a tube shape.
 5. The seal of claim 1, wherein the wovenceramic based fibers include a first set of fibers oriented in a firstdirection and a second set of fibers oriented in a second direction andwoven with the first set of fibers, and the first set of fibers isangled with respect to the bend axis at an angle between about 0 and 60degrees.
 6. The seal of claim 1, wherein the woven ceramic based fibersinclude a first set of fibers oriented in a first direction and a secondset of fibers oriented in a second direction and woven with the firstset of fibers, wherein the relative volume fractions of the first set offibers and the second set of fibers is between about 5% and 60%.
 7. Theseal of claim 1, wherein the woven ceramic based fibers include a firstset of fibers oriented in a first direction and a second set of fibersoriented in a second direction and woven with the first set of fibers,wherein the relative volume fractions of the first set of fibers and thesecond set of fibers is between about 5% and 60%, and wherein the firstset of fibers is angled with respect to the bend axis at an anglebetween about 0 and 60 degrees.
 8. The seal of claim 1, wherein thewoven ceramic based fibers include a first set of fibers oriented in afirst direction, a second set of fibers oriented in a second directionand woven with the first set of fibers, and a third set of fibersoriented in a third direction and woven with the first and second setsof fibers.
 9. A sealed assembly, comprising a first component; a secondcomponent; and a seal sealing the first component with respect to thesecond component, the seal including a ceramic matrix composite plyhaving woven ceramic-based fibers in a ceramic-based matrix, the ceramicmatrix composite ply having at least one bend formed about a bend axisand defining at least one rounded portion.
 10. The sealed assembly ofclaim 9, wherein the at least one bend includes a first bend and asecond bend.
 11. The sealed assembly of claim 10, wherein the first bendis formed about a first bend axis and the second bend is formed about asecond bend axis, wherein the first bend axis and second bend axis areparallel to one another.
 12. The sealed assembly of claim 9, wherein theat least one bend defines a tube shape.
 13. The sealed assembly of claim9, wherein the woven ceramic based fibers include a first set of fibersoriented in a first direction and a second set of fibers oriented in asecond direction and woven with the first set of fibers, and the firstset of fibers is angled with respect to the bend axis at an anglebetween about 30 and 60 degrees.
 14. The sealed assembly of claim 9,wherein the woven ceramic based fibers include a first set of fibersoriented in a first direction and a second set of fibers oriented in asecond direction and woven with the first set of fibers, wherein therelative volume fractions of the first set of fibers and the second setof fibers is between about 5% and 60%.
 15. The sealed assembly of claim9, wherein the woven ceramic based fibers include a first set of fibersoriented in a first direction and a second set of fibers oriented in asecond direction and woven with the first set of fibers, wherein therelative volume fractions of the first set of fibers and the second setof fibers is between about 5% and 60%, and wherein the first set offibers is angled with respect to the bend axis at an angle between about30 and 60 degrees.
 16. The sealed assembly of claim 9, wherein each ofthe first and second components have at least one mating face matingwith the seal, and the at least one mating face is non-abrasive withrespect to the seal.
 17. The sealed assembly of claim 9, wherein thesealed component is in a gas turbine engine.
 18. A method of making aseal, comprising: forming a single ceramic matrix composite plycomprising woven ceramic-based fibers in a ceramic-based matrix toinclude at least one bend about a bend axis, wherein the wovenceramic-based fibers define a weave direction, the woven ceramic basedfibers include a first set of fibers oriented in a first direction and asecond set of fibers oriented in a second direction and woven with thefirst set of fibers, and the first set of fibers is angled with respectto the bend axis at an angle between about 0 and 60 degrees.
 19. Themethod of claim 18, wherein the forming includes forming a first bend,and forming a second bend after forming the first bend.
 20. The methodof claim 18, wherein the forming includes introducing the at least onebend into the ceramic matrix composite ply, and rigidizing the ceramicmatrix composite ply after introducing the bend.